View full sizeRusty Costanza, The Times-PicayuneConstruction of the sector gate at the Caernarvon Canal was photographed March 18.

The 56-foot-wide steel gate in the Caernarvon Canal stands 26 feet above sea level and ties the entire "Chalmette Loop'' levee system into the Mississippi River levee near the border of St. Bernard and Plaquemines parishes.

That 23-mile loop, expected to be completed by the start of hurricane season on June 1, consists of a series of large sector and roadway gates and levees topped with concrete inverted T-walls. It forms a ring from the surge barrier at the Inner Harbor Navigation Canal down along the shoreline of the Mississippi River-Gulf Outlet to Verret and then back west to meet the Mississippi River levee at Caernarvon.

The first contract in the loop was awarded July 2009, for the northernmost section of floodwall. The projects are designed to protect St. Bernard from storm surge flooding caused by hurricanes with a 1-percent chance of occurring in any year, often referred to as a 100-year storm.

While there are are 350 miles in that total New Orleans
area hurricane risk reduction levee system -- officially called the Hurricane and Storm Damage
Risk Reducation System or HSDRRS -- covering five parishes, there are only 120 perimeter miles
that will reach the 100-year level of protection by June 1. The rest is
all interior to the system and now a secondary line of risk reduction,
or in Plaquemines Parish on a different schedule for completion, according to the corps.

The lowest levees in the St. Bernard loop now will be about 26 feet above sea level. During Hurricane Katrina the lowest levees in the parish stood about 14 feet, according to the corps.

And while the previous I-walls were concrete walls sitting atop sheet pilings driven deep enough to block water from moving beneath them, inverted T-walls also include a concrete platform at their base and a series of deeper, square pilings installed at angles to provide better stability.

The corps says the loop floodwalls will consist of 300,000 cubic yards of concrete, nearly two times that of the Superdome. It also is projected to contain 207,000 tons of steel, nearly 30 times the amount of metal to construct the Eiffel Tower.

Calling the loop incredible, St. Bernard President Craig Taffaro said the parish "has never had this type of protection in its history," but cautioned that "our coastal restoration is equally important."

"You can't just depend on the walls," he said. "This is not intended to be our front line of defense."

The 95-ton steel gate leaves, fabricated in Morgan City and made from reinforced concrete and steel, will cross the Caernarvon Canal and are 36 feet long - 10 feet below the water, 26 feet above. The $46.9 million contract was awarded to New Jersey-based Conti Federal Services, Inc. in June 2010.

Earlier this month, the corps poured concrete for the final section of floodwall along the MR-GO between Bayou Dupre and Louisiana 46. The approximate 7.5-mile stretch was built by St. Bernard Levee Partners, LLC, a joint venture of URS Corporation, James Construction, Inc., and Obayashi Corporation, for $281 million. It measures 26 to 32 feet above sea level and runs parallel to the former MR-GO shipping channel.

It was the third St. Bernard risk reduction project to achieve the 100-year storm design elevation, according to the corps.

The floodwall running along the MR-GO between Bayou Bienvenue and Bayou Dupre achieved the 100-year level of risk reduction in March. The vehicle gate at Louisiana 46 also has achieved that risk reduction level.

Additional risk reduction features still under construction in St. Bernard include an about 8-mile floodwall between Louisiana 46 in Verret and the Caernarvon Canal, floodwall tie-ins at the recently-installed Bayou Dupre sector gate, floodwalls that cross the Caernarvon Canal and tie into the Mississippi River levee, a highway gate at Louisiana 39 and a railroad gate for the adjacent Norfolk Southern Railroad crossing in Caernarvon.

Questions and comments related to construction impacts may be addressed to the Corps' Construction Impacts Hotline at 877.427.0345.